This invention relates to hand tools, and in particular the invention is concerned with a compact hand tool for projecting a plumb reference beam of visible light for precise alignment.
Many self-leveling plumb laser beam generators use ball bearings, wires, and springs to do the self-leveling function. There are also many instruments which use electronic sensors and motors for automatically leveling or plumbing laser beam projectors as required.
A low cost automatic self-leveling laser instrument is described in U.S. Pat. Nos. 5,459,932, 5,524,352, 5,541,727, and 5,619,802, assigned to the same assignee as the present invention. The disclosure of those patents is incorporated herein by reference. In these embodiments the laser projector is mounted on a pendulous platform which requires that the electrical power be carried to the moving pendulum via fine wires as shown schematically in FIG. 1. Other elements necessary for the self-leveling function are also shown. The subject invention is similar in application to the above-referenced patents.
U.S. Pat. No. 4,912,851 is also relevant to this invention in disclosing a plumb beam generator with optical tilt correction.